1. Field of the Invention
The invention relates to a scaffolding system or framework for various tasks and various fields of application comprising tubular standards and horizontal and/or diagonal scaffold members whereby one or several scaffold joints placed above each other at a distance from each other are arranged on each tubular standard, with said joints the connecting scaffold members engage.
2. Description of the Related Art
Scaffolds of this type have been state-of-the-art for years.
From U.S. Pat. No. 3,420,557, a scaffold is known, in which the scaffold joints have four wedge pockets, with which horizontal and diagonal scaffold members engage through wedge-shaped plug-in elements. Hereby it is a disadvantage that for mounting of a horizontal scaffold member the connecting head of the member is connected to the wedge pocket through a separate, captive wedge. The wedge heads of the diagonal scaffold member proposed here are rotatably connected to the ends of a diagonal brace through rivet joints that can bear only small mechanical loads.
The decisive criterion for the service features of modular scaffolding systems is the loadability of the joint when horizontal and diagonal scaffold members are connected, which is specified by the so-called joint factors. The most relevant joint factors describing the joint loadability are the permissible bending moments and the lateral, normal and diagonal loads. The higher these values are, the more economic structures can be erected because less material is necessary.
Modular scaffolding systems known on the world market, like Layher, Plettac, Rux, Hunnebeck-Roro, Cuplok, etc., use scaffold joints differing only little in their design, and therefore have approximately identical levels of economic efficiency and service features. The structure of the scaffold joints known up to now is characterized by the perforated disc and perforated shell design to EP-A-0389 933, WO 97/49880 (published Dec. 31, 1997) or DE-A-37 15 296, respectively, or the disc and cup shape with pole rosettes to EP-A-0116 679.
For modular scaffolds, scaffold bars as spacer members are by means of joint elements horizontally and vertically assembled to two- or three-dimensional scaffolding structures to be used as fa.cedilla.ade, room or other scaffolds. To achieve more service variability, improved service properties, more economical design capabilities, reduced manufacturing effort for modular scaffolds and their system elements, and effective less time-consuming assembly, solutions requiring less material, with higher joint loadabilities, or joint factors, for modular scaffolding systems are demanded.
These system elements have to be designed and must interact in performing their function when mechanically jointed to structures in order to bear forces, loads and bending moments in such a way that all safety-relevant requirements are reliably fulfilled. The safety-relevant requirements also concern the incorporation of lift-off protectors, which has been required up to now. Lift-off protectors are system elements with safety devices additionally required in order to protect the scaffold plates from being lifted off by the action of wind or storm.
Vertical diagonal braces and horizontal diagonal braces (diagonal scaffold members) are necessary to accept and carry off diagonal forces in modular scaffolds and, therefore, also in truss structures of scaffold members to ensure the stability and safety required.
The vertical diagonal braces known in the market, which are used in the modular scaffold systems of most manufacturers, can accept only relatively small diagonal loads at the scaffold joint.
The relatively small permissible load values result from the constructional structure of the known vertical diagonal braces. For the known disk, plate or cup types of joint connection, the maximum permissible diagonal load application of the scaffold joint is relatively small and hence, only little suited for special truss structures made of tubular standards, horizontal scaffold members and diagonal scaffold members.
A modular scaffold joint with substantially improved joint factors is described in EP-B-0622 504. A scaffold joint to this solution has four wedge pockets, with which the connecting members engage through wedge-shaped plug-in elements.
Wedge pockets and wedge-shaped plug-in elements have similar fit shapes with the wedge pockets having parallel walls.